Casualties due to "friendly fire" have been an unfortunate element of warfare throughout history. Often, such casualties occur because the technology to identify a potential target as friendly under the fog of war has not always kept pace with the technology to acquire that target and destroy it.
In Operation DESERT STORM, a simple apparatus was used to identify friendly vehicles. This apparatus, installed in each friendly vehicle, merely emitted an infra-red beacon. Unfortunately, such a beacon will also serve to positively identify the vehicle to a moderately sophisticated enemy. What is needed is an electronic identification system which determines whether or not a "target" is friendly without bringing either the targeting vehicle or the target vehicle to the attention of the enemy.